Runners who missed breakfast
One portable snack may appeal before a light jog or parkrun when a meal is not practical. The UK Sports Institute says many athletes eat one to three hours before running, but timing varies between individuals.
Who is choosing a bar?
Runners comparing individual portions
Check carbohydrate for one bar, not just the pack size or a per-100 g figure. The Tesco-listed Mallow & Marsh bar has 27.1 g carbohydrate per 35 g bar, while its Kellogg's Rice Krispies Squares listing gives 21 g per 28 g bar.
Runners checking ingredients
Gelatine sources and declarations for milk, cereals and other allergens differ between these products. Fibre and polyols also matter when deciding whether a particular bar is familiar enough to eat close to a run.
What should you check?
Start with whether you want a snack at all, then compare one bar's label and consider when you would eat it.
| Priority | What to check | Your needs |
|---|---|---|
| Whether to take a bar | Consider your preceding meal and when you plan to run. The UK Sports Institute says a short run does not call for marathon-style fuelling. | If I have already eaten breakfast, I may not want another snack. If I missed it, one familiar portion may be more practical than a full meal. |
| Carbohydrate per bar | Compare the individual serving and pack format. Tesco Groceries lists 27.1 g carbohydrate per 35 g Mallow & Marsh bar and 21 g per 28 g Kellogg's bar; ASDA Groceries lists 17 g per 22 g Rice Snaps bar. | I want to know what is in the portion I would carry, rather than choose by the words ‘marshmallow’ or ‘protein’ on the front. |
| Timing and ingredients | Try the chosen portion in training. The UK Sports Institute says many athletes eat one to three hours before running; ASDA Groceries lists 12 g fibre and 9 g polyols in the 65 g Optimum Nutrition bar, whose label warns about excessive consumption. | A familiar bar and a timing that works for me matter more than trying an unfamiliar snack on event day. |
| Dietary suitability | Read the current pack for allergens, precautionary statements and gelatine. Tesco Groceries lists beef gelatine in the Mallow & Marsh and Kellogg's products; ASDA Groceries lists pork gelatine in Rice Snaps. | I need the actual recipe and allergen declarations to fit my dietary requirements, not just the flavour name. |
Common buying mistakes
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Assuming every 5K needs extra fuel
A bar may be unnecessary if you have already eaten. The UK Sports Institute advises that a parkrun does not require marathon-style fuelling.
Consider your earlier meal and whether you actually want a snack; test any bar during training rather than introducing it on event day.
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Choosing by protein content alone
ASDA Groceries lists 20 g protein but 17 g carbohydrate, 12 g fibre and 9 g polyols per Optimum Nutrition Marshmallow Crunch bar. Its label warns that excessive consumption may cause laxative effects.
If your aim is to compare carbohydrate portions, read the per-bar carbohydrate figure first and consider whether you have tolerated the ingredients near a run.
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Overlooking gelatine and allergens
Marshmallow-style bars can use different gelatine sources and have different allergen declarations, so a familiar product name does not establish dietary suitability.
Check the current pack, including ‘may contain’ information, for the exact product and flavour you intend to eat.
Brand references
Mallow & Marsh
Its Vanilla & Milk Chocolate product is a chocolate-coated marshmallow bar sold as a 35 g portion.
- Tesco Groceries lists 27.1 g carbohydrate per bar.
- It contains milk, soya and beef gelatine, and may contain peanuts, tree nuts and egg.
Kellogg's Rice Krispies Squares
The Marshmallow cereal square is a 28 g bar available in multipacks.
- Tesco Groceries lists 21 g carbohydrate per bar.
- Its listed ingredients include barley, wheat, milk and beef gelatine; check the current pack for precautionary allergen information.
Optimum Nutrition
Marshmallow Crunch is a 65 g protein bar that the manufacturer positions for use after training.
- ASDA Groceries lists 20 g protein and 17 g carbohydrate per bar.
- The same listing gives 12 g fibre and 9 g polyols per bar and warns that excessive consumption may cause laxative effects.
Myprotein
Crispy Square Marshmallow is a 30 g protein snack bar.
- Tesco Groceries lists 13 g carbohydrate and 5.9 g protein per bar.
- It also lists 5.1 g fibre and maltitol among the ingredients; check the current pack for allergens.
A cereal-and-marshmallow option on Joybuy
This eight-bar pack provides individually portioned cereal-and-marshmallow squares to consider if you want to try the same 28 g portion during training. It is not a single-bar retail pack.
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Kellogg's Rice Krispies Squares Marshmallow Snack Bars, 8 x 28g
The individually portioned bars let you try a consistent serving during training before deciding whether to eat one near a 5K. Each 28 g bar lists 21 g carbohydrate. Contains barley, wheat and milk; may contain cereals containing gluten and soya. Check the current pack against your dietary requirements.
Questions about bars and 5K runs
Do I need a marshmallow bar for a 5K?
No bar is automatically needed. The UK Sports Institute says runners need not fuel for a parkrun as though it were a marathon; whether you want a small snack depends on your earlier meal, hunger and experience with eating before running.
When should I try a bar before running?
Try it in ordinary training, not for the first time on event day. The UK Sports Institute says many athletes eat one to three hours before running, while individual timing varies.
Can I assume a marshmallow bar meets my dietary requirements?
No. Tesco Groceries lists beef gelatine in the Mallow & Marsh and Kellogg's bars, while ASDA Groceries lists pork gelatine in Rice Snaps. Allergen declarations also differ, so read the current pack for the exact product.
What changes if I choose a protein-focused bar?
Compare its full per-bar label rather than protein alone. ASDA Groceries lists 20 g protein, 17 g carbohydrate, 12 g fibre and 9 g polyols in the 65 g Optimum Nutrition Marshmallow Crunch bar; the manufacturer positions it for after training, and the label warns about excessive consumption.